Merge pull request #6 from tjschutte/main

Create Java version of Credit-Card-Product service, and switch application to use it.

.gitignore

@@ -10,3 +10,7 @@ infrastructure/templates/pgt-proxy/docker_image_builder_*
 infrastructure/templates/application/docker_image_builder_*
 application/frontend/node_modules
 application/frontend/run.sh
+application/java-credit-card-product-service/target
+*.jar*
+*.class
+*.lst

README.MD

@@ -1,11 +1,90 @@
 # Notes
 
+This repo is for the Ambar Event Sourcing / Microservices courses. 
+You can use this repo to deploy a real world credit card application which leverages both event sourcing and microservices 
+to create a larger application. Note that this is an academic example, implemented in multiple languages and with multiple 
+components - you should not expect to deeply understand everything in all the languages.
+
 ## Preparation Steps
 
+These steps will be performed with your instructor during the first coding session of your course, and will allow you to
+deploy this repo into a cloud environment running on Google Cloud Platform (GCP)
+
 1. Fork this repository
 2. Create two GitHub action secrets (provided by your course instructor) as follows:
 ```
 STATE_MANAGEMENT_BASE64=some_string_here
 CREDENTIALS_BASE64=some_string_here
 ```
-3. Make a blank commit, and push it to GitHub.
+**N.B. Make sure to enter the entire string for each secret, with no quotes, and no newlines!**
+3. Make a trivial commit (such as updating this readme), and push it to GitHub.
+
+## Extending this program
+
+Our sample application attempts to model a financial institution which offers different credit cards (products). We have
+already modeled some services of the application - some multiple times in multiple languages! To get started, you should
+look at one of the already modeled services like the Credit-Card-Product service which is implemented in multiple languages
+and try to follow along in one of the languages you are familiar with (php, java). Reimplement the service in your language
+of choice, or add any missing features to the module.
+
+Once you have an understanding of the pattern as it works in your chosen implementation language, feel free to implement
+another service of the application. If you feel inclined, open a pull request to the Ambar repo, and we will review and merge 
+it and extend the frontend application to leverage the capabilities!
+
+### Event Sourcing Additional Context / Reminders
+
+A quick reminder on Event Sourcing
+
+Event Sourcing is the inversion of state in an application. Instead of directly storing state in a record and performing CRUD
+operations on those records, we record series of events that describe what happened in our application and derive state from
+one or more of those events. This gives us a direct historical event sequence that we can use to build up state in many ways
+and to even 'time travel' to see what state was in the past, without the need for audit tables or trying to deal with the
+dual write problem.
+
+Note: This does not mean we do not directly store state in event sourcing! We can still distill information from our events
+to build useful models about the state of our application and its data. This is where projections and read models come in.
+
+An easy way to organize event sourcing conceptually, and in code, is by leveraging the Command Query Responsibility Separation
+pattern (CQRS) where we create distinct paths for our write (record events) and read (leverage events / state) actions.
+
+#### Terms refresher
+
+* **Command**: A request for something to happen in our application.
+  * E.G. Making a new credit card product for customers to apply for.
+* **Event**: A recording of something significant happening in our application containing things like who, what, and when.
+Events should be small and precise, and are written sequentially to an immutable log. Never change events or insert new ones 
+except at the tail of the log. Events should belong to short-lived processes, such as handling a request or system notification.
+  * E.G. Activating a credit card product so customers can apply for it 
+(Who: The product ID, What: Make it active, When: when was the event recorded)
+* **Aggregate**: Information Model built from a set of related events used to model a process such has handling a command / request.
+They should be small, and leverage event ordering to create a minified state for process handling.
+  * E.G. A Product Aggregate to model a credit card which is offered in our service. We can leverage the aggregate to determine
+if a product is already available (active) or not, to determine if a command (request) is valid.
+* **Projection**: Projection leverages building up some useful state from a filtered set of events and storing the derived
+state into a projection database. These projections can then be leveraged during command validations when determining if
+a command should be accepted (event written) or not.
+* **Query**: Queries are the read side of our application, and leverage the models created by projections to retrieve information
+store about the state of our application.
+
+```
+Comamnd (Read from EventStore/ReadModelStore, write back to EventStore)
+  -> [Command (Request)] -> [Build some state (EventStore Aggregate)] -> [Perform Validations (Aggregate, ReadModels)] -> 
+  [Record whatever happened (New Event)] -> [EventStore]
+
+(Strongly Consistent) ^
+------------------------------------------------------------------------------------------------------------------------
+(Eventually Consistent) v
+
+Reaction (Event from EventStore, write back to EventStore)
+  -> [EventStore(Event)] -> [Build some state (EventStore Aggregate)] -> [Perform Validations (Aggregate, ReadModels)] -> 
+  [Record whatever happened (New Event)] -> [EventStore]
+
+
+Projections (Read from ReadModelStore, write to ReadModelStore)
+  -> [EventStore(Event)] -> [Build some state] -> [Project some interesting state] -> [ReadModelStore]
+
+Querys (Read Commands) (Read from ReadModelStore)
+  -> [ReadModelStore (Modeled State)]
+```
+
+### Microservices Additional Context / Reminders

application/java-credit-card-product-service/.dockerignore

@@ -0,0 +1,2 @@
+code/vendor
+code/development-environment

application/java-credit-card-product-service/CreditCardProduct.iml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module version="4">
+  <component name="FacetManager">
+    <facet type="jpa" name="JPA">
+      <configuration>
+        <setting name="validation-enabled" value="true" />
+        <setting name="provider-name" value="Hibernate" />
+        <datasource-mapping>
+          <factory-entry name="entityManagerFactory" value="e2079969-38fd-4e93-8daa-97fd5223b996" />
+        </datasource-mapping>
+        <naming-strategy-map />
+      </configuration>
+    </facet>
+  </component>
+</module>

application/java-credit-card-product-service/Dockerfile

@@ -0,0 +1,30 @@
+# Step 1: Use Maven image to build the application
+FROM maven:3.9.5-eclipse-temurin-21 AS build
+
+# Set the working directory inside the container
+WORKDIR /app
+
+# Copy the pom.xml and download dependencies (layer caching)
+COPY pom.xml .
+RUN mvn dependency:go-offline
+
+# Copy the rest of the application source code
+COPY src ./src
+
+# Build the Spring Boot application
+RUN mvn clean package -DskipTests
+
+# Step 2: Use JDK 21 runtime image to run the application
+FROM eclipse-temurin:21-jdk
+
+# Set the working directory for the runtime container
+WORKDIR /app
+
+# Copy the JAR file from the build image to the runtime image
+COPY --from=build /app/target/*.jar app.jar
+
+# Expose port 8080 (Spring Boot default port)
+EXPOSE 8080
+
+# Set the entry point to run the application
+ENTRYPOINT ["java", "-jar", "app.jar"]

application/java-credit-card-product-service/development-environment/.gitignore

@@ -0,0 +1 @@
+data

application/java-credit-card-product-service/development-environment/dev-commands.sh

@@ -0,0 +1,41 @@
+endpoint="localhost:8080"
+
+# To create the Starter card
+curl -X POST "${endpoint}/api/v1/credit_card_product/product" \
+-H "Content-Type: application/json" \
+-d '{
+  "productIdentifierForAggregateIdHash": "STARTER_CREDIT_CARD",
+  "name": "Starter",
+  "interestInBasisPoints": 1200,
+  "annualFeeInCents": 5000,
+  "paymentCycle": "monthly",
+  "creditLimitInCents": 50000,
+  "maxBalanceTransferAllowedInCents": 0,
+  "reward": "none",
+  "cardBackgroundHex": "#7fffd4"
+}'
+
+# To create the Platinum card
+curl -X POST "${endpoint}/api/v1/credit_card_product/product" \
+-H "Content-Type: application/json" \
+-d '{
+  "productIdentifierForAggregateIdHash": "PLATINUM_CREDIT_CARD",
+  "name": "Platinum",
+  "interestInBasisPoints": 300,
+  "annualFeeInCents": 50000,
+  "paymentCycle": "monthly",
+  "creditLimitInCents": 500000,
+  "maxBalanceTransferAllowedInCents": 100000,
+  "reward": "points",
+  "cardBackgroundHex": "#E5E4E2"
+}'
+
+# To list the current card products
+curl -X POST "${endpoint}/api/v1/credit_card_product/product/list-items" | jq .
+
+productId=""
+# Activate a product
+curl -X POST "${endpoint}/api/v1/credit_card_product/product/activate/${productId}"
+
+# Deactivate a product
+curl -X POST "${endpoint}/api/v1/credit_card_product/product/deactivate/${productId}"

application/java-credit-card-product-service/development-environment/dev_a_start.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+set -e
+
+#docker run --rm -v $(pwd):/app composer:2.2.24 install --ignore-platform-reqs
+docker compose down
+docker compose up -d --build --force-recreate
+sleep 5

application/java-credit-card-product-service/development-environment/dev_z_shutdown.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+set -e
+
+docker compose down

application/java-credit-card-product-service/development-environment/docker-compose.yml

@@ -0,0 +1,84 @@
+services:
+
+  java-credit-card-product:
+    container_name: java-credit-card-product
+    build:
+      context: ./../
+    volumes:
+      - ./../:/srv
+    restart: always
+    environment:
+      EVENT_STORE_HOST: "172.30.0.102"
+      EVENT_STORE_PORT: 5432
+      EVENT_STORE_DATABASE_NAME: "my_es_database"
+      EVENT_STORE_USER: "my_es_username"
+      EVENT_STORE_PASSWORD: "my_es_password"
+      EVENT_STORE_CREATE_TABLE_WITH_NAME: "event_store"
+      EVENT_STORE_CREATE_REPLICATION_USER_WITH_USERNAME: "replication_username_test"
+      EVENT_STORE_CREATE_REPLICATION_USER_WITH_PASSWORD: "replication_password_test"
+      EVENT_STORE_CREATE_REPLICATION_PUBLICATION: "replication_publication_test"
+      MONGODB_PROJECTION_HOST: "172.30.0.103"
+      MONGODB_PROJECTION_PORT: 27017
+      MONGODB_PROJECTION_AUTHENTICATION_DATABASE: "admin"
+      MONGODB_PROJECTION_DATABASE_NAME: "projections"
+      MONGODB_PROJECTION_DATABASE_USERNAME: "my_mongo_username"
+      MONGODB_PROJECTION_DATABASE_PASSWORD: "my_mongo_password"
+      SESSION_TOKENS_EXPIRE_AFTER_SECONDS: 3600
+    depends_on:
+      - pg-event-store
+      - mongo-projection-reaction
+    networks:
+      TestNetwork:
+        ipv4_address: 172.30.0.101
+    deploy:
+      resources:
+        limits:
+          cpus: '0.500'
+          memory: 1024M
+
+  pg-event-store:
+    build:
+      context:
+        ./pg-event-store
+    container_name: pg-event-store
+    restart: always
+    volumes:
+      - ./data/event-store/pg-data:/var/lib/postgresql/data
+    environment:
+      POSTGRES_USER: my_es_username
+      POSTGRES_DB: my_es_database
+      POSTGRES_PASSWORD: my_es_password
+    command: >
+      postgres -c wal_level=logical
+               -c ssl=on
+               -c ssl_cert_file=/var/lib/postgresql/certs/server.crt
+               -c ssl_key_file=/var/lib/postgresql/certs/server.key
+    expose:
+      - 5432
+    networks:
+      TestNetwork:
+        ipv4_address: 172.30.0.102
+
+  mongo-projection-reaction:
+    build:
+      context:
+        ./mongo-projection-reaction
+    container_name: mongo-projection-reaction
+    restart: always
+    environment:
+      MONGO_INITDB_ROOT_USERNAME: my_mongo_username
+      MONGO_INITDB_ROOT_PASSWORD: my_mongo_password
+    volumes:
+      - ./data/mongo-projection-reaction/db-data:/data/db
+    expose:
+      - 27017
+    networks:
+      TestNetwork:
+        ipv4_address: 172.30.0.103
+
+networks:
+    TestNetwork:
+        driver: bridge
+        ipam:
+            config:
+                - subnet: 172.30.0.0/24

application/java-credit-card-product-service/development-environment/mongo-projection-reaction/Dockerfile

@@ -0,0 +1 @@
+FROM mongo:7.0.14

application/java-credit-card-product-service/development-environment/pg-event-store/Dockerfile

@@ -0,0 +1,9 @@
+FROM postgres:16.4
+
+RUN mkdir -p /var/lib/postgresql/certs
+RUN openssl genrsa -out /var/lib/postgresql/certs/server.key 2048
+RUN chmod 600 /var/lib/postgresql/certs/server.key
+RUN openssl req -new -key /var/lib/postgresql/certs/server.key -out /var/lib/postgresql/certs/server.csr -subj "/C=GB/ST=London/L=London/O=SnakeOil/OU=Org/CN=snake-oil.oil"
+RUN openssl x509 -req -in /var/lib/postgresql/certs/server.csr -signkey /var/lib/postgresql/certs/server.key -out /var/lib/postgresql/certs/server.crt -days 36500
+RUN chown 999 /var/lib/postgresql/certs
+RUN chown 999 /var/lib/postgresql/certs -Rf

application/java-credit-card-product-service/pom.xml

@@ -0,0 +1,79 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>3.3.4</version>
+		<relativePath/> <!-- lookup parent from repository -->
+	</parent>
+	<groupId>cloud.ambar</groupId>
+	<artifactId>CreditCardProduct</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<name>CreditCardProduct</name>
+	<description>Ambar Credit Card Product service for course demo</description>
+	<url/>
+	<licenses>
+		<license/>
+	</licenses>
+	<developers>
+		<developer/>
+	</developers>
+	<scm>
+		<connection/>
+		<developerConnection/>
+		<tag/>
+		<url/>
+	</scm>
+	<properties>
+		<java.version>21</java.version>
+	</properties>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-web</artifactId>
+		</dependency>
+
+		<!-- Java Persistence API -->
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-data-jpa</artifactId>
+		</dependency>
+
+		<!-- Database Drivers -->
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-data-mongodb</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.postgresql</groupId>
+			<artifactId>postgresql</artifactId>
+		</dependency>
+
+		<!-- Lombok for reducing boilerplate code -->
+		<dependency>
+			<groupId>org.projectlombok</groupId>
+			<artifactId>lombok</artifactId>
+			<version>1.18.30</version>
+			<scope>compile</scope>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+				<version>${project.parent.version}</version>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>